Recovery Storage Groups Explained

Disaster recovery is one of the biggest problems facing Exchange Server administrators. Although Exchange is easier to recover than many other messaging systems, you must still deal with many small details to complete a successful recovery. More importantly, to ensure a successful restoration of service, you must prepare and test your recovery processes before you need them. One of the most common requests from Exchange customers has been a simpler way to handle common disaster-recovery scenarios. Microsoft has been listening, apparently, because Exchange Server 2003 contains a new feature that simplifies a common scenario--the recovery of one database.

Exchange Server 5.5 supports only one private and one public store per server, so recovering one database is logically equivalent to restoring the whole server. Exchange 2000 Server supports as many as 20 databases (four storage groups--SGs--with 5 databases each), but to restore one of these databases, you must fuss with a variety of Active Directory (AD) objects, which increases the complexity of the operation. Exchange 2003, however, introduces the Recovery Storage Group, a new kind of Exchange object that looks somewhat like a regular SG but has some important differences.

The Recovery Storage Group's purpose is simple: It lets you restore a database and its mailboxes without using a separate recovery server. This ability is invaluable when you need to restore just one mailbox. When you use an Exchange-aware backup program, the Recovery Storage Group lets you mount a mailbox database from backup onto any other Exchange server in the same administrative group as the server on which the original database resided. You can then copy data from the Recovery Storage Group's databases (however, you can't create new mailboxes in the Recovery Storage Group, and many regular SG settings are unavailable in Recovery Storage Groups). You can have one Recovery Storage Group per server.

The Recovery Storage Group works because the Exchange backup API transparently intercepts restored data; if a Recovery Storage Group exists, Exchange acts as though the Recovery Storage Group is the only SG on the server and directs all database restores to the Recovery Storage Group. You can then use our old friend ExMerge, which has received a makeover to support Recovery Storage Groups, to access a mailbox in the Recovery Storage Group--without first associating that mailbox with an AD user account. (The user account must exist, however, for ExMerge to access the mailbox data. Recovery Storage Groups won't solve the problem of losing mailbox data when you delete an AD account.) To return the Exchange Store to its regular restore behavior, simply remove the Recovery Storage Group.

Recovery Storage Groups provide a welcome improvement in Exchange recoverability. When you couple the Recovery Storage Group's "restore-anywhere" functionality with a solid backup strategy, you'll find that those occasional frenzied recovery sessions engender a little less panic. To learn more about Recovery Storage Groups, see the Exchange 2003 online Help (look for "Recovery Storage Group"). You can also expect to see whitepapers that describe the technology more fully from Microsoft and from third-party vendors who want to leverage Recovery Storage Groups in their products.

Discuss this Article 6

Anonymous User (not verified)

on Jun 14, 2005

I would recommend taking a look at Power Controls sold by Ontrack Data Recovery. http://www.ontrack.com/powercontrols/
I use it and it is great timesaver. It will also handle recovering Public Folder Data, extract from tape to disk with no recovery/ restore server and contains a powerful searching tool for finding messages containing keyword, user name, date etc. Good luck. Pete Low.

I found this comment particularly amusing 'although exchange is easier to recover than many other messaging systems' and would like to know what 'other messaging systems' Paul is referring to in the article.

I don't think this article was sritten from experience, but more out of reading from a manual.
I've had a lot of time to work on Exchange 2003, and we are ready to roll it
out in the coming weeks. However, I don't really understand the point of
the recovery Storage Group. Check out PSS ID Number: 824126 "How to Use
Recovery Storage Groups in Exchange Server 2003"
If I delete a mailbox in Exchange 2003, I can't recovery it with the
Recovery Group:
"The first test that a mailbox must pass before you can recover data from
the mailbox by using a Recovery Storage Group is that the mailbox GUID must
correspond to a user in Active Directory.
The mailbox GUID is a unique value that distinguishes a mailbox from all
others. The mailbox GUID is created in the mailbox store when the mailbox is
created, and the value remains the same for the lifetime of the mailbox. The
msExchMailboxGUID attribute uses the mailbox GUID value from the mailbox
store. The msExchMailboxGUID attribute is set on the user who owns the
mailbox when you link a mailbox to a user account in Active Directory. The
Exmerge.exe tool uses the msExchMailboxGUID attribute to match the mailbox
in the Recovery Storage Group with the original mailbox.
When you delete a mailbox, mailbox attributes are removed from the user
object in Active Directory that previously owned the mailbox. As a result,
you cannot use a Recovery Storage Group to recover a deleted mailbox. "
My question is, what's the point of a recovery store, when I can't recovery
a mailbox? We've tried many times, many different ways, even tried to
change the msExchMailboxGUID to match what it was originally, but the
exmerge.log file displays the msExchMailboxGUID differently, and they don't
match.
Any ideas?